JPH077256B2 - How to generate a gray scale pattern - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a method of generating a low resolution gray scale pattern that represents a high resolution original character image.

B. Prior Art and Problems Two-level display or on-off display for displaying or printing a dot matrix pattern of characters,
It has been used in CRT displays, plasma displays, liquid crystal displays or various printers. In a two level display, a binary value is assigned to each pixel (pel). Thus, each pel in the matrix represents black or white. However, when two-level display is performed in a matrix, a staircase display is generated along a non-vertical line or a non-horizontal line. As the resolution of the displayed or printed image decreases, this stepped edge grows and is discomforting to the viewer.

Display systems using multiple gray scale levels have been developed to provide a more natural text display. Communication of the ACM, 1980, Volume 14, Volume 3
Issue 302-307, John E. Wamock, "The Dis
play of Characters Using Gray Level Sampling Array
S. "and U.S. Pat. No. 4,158,200, Charles L. Seitz et al., Burroughs, Inc., describe the above-described system using a plurality of different gray scale levels or intensities.

FIG. 7 illustrates the concept of display using different Grace Scale levels. High resolution character patterns, such as 88x88 dots / character box, are stored in the font memory. Suppose a character pattern is displayed on a display device with a resolution of 11 × 11 dots. In this case, the sampling pattern 21 having an 8 × 8 sampling window is used. To convert an 88x88-dot original character pattern into an 8x8-dot character image, the number of black pels in a portion of the original character image surrounded by one sampling window is counted, and this sampling window One of eight gray scale levels is assigned according to the number of black pels in the resulting gray scale pattern 29. This is used to control the brightness level of the display device.

Although displaying with gray scale levels solves the problem of staircase edges, this creates new problems when relatively complex characters are displayed, such as Chinese characters containing many horizontal and vertical lines. . Referring to FIG. 14, high resolution kanji stored in the font memory
51 is shown. In this case, a sampling pattern with a 16 × 16 sampling window is used. As described in FIG. 7, the number of black pels counted in each sampling window is assigned a gray scale value to produce a gray scale pattern 52 representing the original Chinese character 51. The gray scale pattern 52 is then sent to the display device. This gray
It is clear that the pattern 53 displayed using the scale pattern 52 has horizontal lines touching each other of the same gray level and is difficult to read.

C. Means for Solving the Problems A method of generating a low resolution gray scale pattern representing a high resolution original character image according to the present invention comprises a number of lines determined by the ratio of the low resolution and the high resolution. And generating a sampling pattern having a plurality of sampling windows arranged in columns, and sequentially positioning the sampling patterns at a plurality of positions separated by a predetermined distance along the column direction on the original character image. Then, the total number of black pels in all rows is counted by adding the number of black pels in a predetermined portion of each row of the sampling pattern at each of the above positions, and the maximum black is calculated by comparing the total number of black pels at each of the above positions. The position where the pel number is detected is detected, and the sampling pattern is placed at the detected position on the original character image. Positioning, counting the number of black pels in each sampling window of the sampling pattern, and assigning each sampling window one of a different gray scale value.

In the method of the invention, a group of pel lines located in the central portion of the sampling window is
Used to count the number of black pels in the row.

In the method of the present invention, the sampling patterns are sequentially positioned at a plurality of positions separated by one pel line.

A method of generating a low resolution gray scale pattern representing a high resolution original character image in accordance with the present invention comprises a plurality of samplings arranged in a number of rows and columns determined by the ratio of the low resolution and the high resolution. Generating a sampling pattern having a window and sequentially positioning the sampling pattern at a plurality of positions separated by a predetermined distance along the row direction and the column direction on the original character image, and at each of the positions, Counting the total number of black pels in all rows by adding the number of black pels in each row of the above sampling pattern, and the total number of black pels in all columns by adding the number of black pels in each row. Comparing the total number of black pels in each of the positions,
The position in the column direction in which the total number of black pels in all the rows is the maximum and the position in the row direction in which the total number of black pels in the all columns is the maximum are detected, and the position is detected at the detection position on the original character pattern. Positioning the sampling pattern, counting the number of black pels in each sampling window of the sampling pattern and assigning each sampling window one of a different gray scale value.

A method of generating a low resolution gray scale pattern representing a high resolution original character image in accordance with the present invention comprises a plurality of samplings arranged in a number of rows and columns determined by the ratio of the low resolution and the high resolution. Generating a sampling pattern having a window and sequentially positioning the sampling pattern at a plurality of positions separated by a predetermined distance along the row direction and the column direction on the original character image, and at each of the positions, Counting the total number of black pels in all rows by adding the number of black pels in each row of the above sampling pattern, and the total number of black pels in all columns by adding the number of black pels in each row. Comparing the total number of black pels in each of the positions,
The position in the column direction in which the total number of black pels in all the rows is the maximum and the position in the row direction in which the total number of black pels in the all columns is the maximum are detected, and the position is detected at the detection position on the original character pattern. Position the sampling pattern, count the number of black pels in each row and column of the sampling pattern, compare the number of black pels in each row, and select the row with more black pels than the adjacent row. Selecting columns having more black pels than adjacent columns by comparing the number of black pels in the columns, and at a plurality of positions separated by a predetermined distance along the row direction and the column direction on the original character image, Positioning the selected rows and columns sequentially, counting the number of black pels in the row at each position and the number of black pels in the column, and counting the number of black pels in the selected row at each position. Compare the black pel's There detecting the position of the column having the maximum
The number of black pels in the selected column at each position is compared to detect the position in the row direction where the number of black pels is maximum, and the position of the selected row and column is set to the detected position. Shifting each and counting the number of black pels in each sampling window of the sampling pattern and assigning each sampling window one of a different gray scale value.

D. Description of Embodiments Referring to FIG. 1, there is shown a block diagram of a pattern generation system which operates in accordance with the present invention.

The font memory 1 stores a set of high resolution original character images or patterns. The resolution of the original character image shall be 88x88 dots / character box, and the original character image shall be converted to a gray scale pattern of 8x8 dots / character box or 8x8 pels / character box. The pattern generation system is built into the printer or display and the original character pattern is loaded into the font memory 1 from the processor.

An image of one of the original character patterns with a resolution of 88.times.88 dots, for example the character B, is fetched from the font memory 1 to the buffer memory 2 under the control of the microprocessor 3 as shown in FIG.

The size of the buffer memory 2 shown in FIG. 1 is the same as the size of the box of one original character.

The resolution of the original character pattern, i.e. 88 x 88 dots and the gray scale to be displayed on the display screen.
Based on the resolution of the pattern, i.e. 8x8 dots, the microprocessor 3 produces a grid-like sampling pattern 21 of 8x8 window as shown in FIG. The size of the sampling pattern 21 is equal to the size of the one character box.

The microprocessor 3 performs the image conversion process of the algorithm shown in FIG.

In step 31 of FIG. 3, the microprocessor 3
Is all the pels in the X and Y directions of the original character image.
The number of black pels in the line is counted and a histogram 26 in the X direction and a histogram 27 in the Y direction shown in FIG. 2 are generated, and these histograms 26 and 27 are stored in the histogram buffer memory 4 in FIG. To do.

Operation proceeds to block 32 of FIG. 3 where microprocessor 3 positions sampling pattern 21 in an initial position. In this initial position, sampling
The upper left corner 22 of the pattern 21 is positioned at the upper left corner 23 of the dot matrix or character box of the original character pattern.

Explaining the sampling operation in the row or X direction with reference to FIG. 4A, which is an enlarged view of portion 24 of FIG. 2, pel lines 1-11 represent pel lines of the original character image. The microprocessor 3 selects a group of pel lines 4, 5, 6, 7 and 8 for each row of the sampling pattern 21. The pel line 6 is located at the center of the width of the row as shown in FIG. Microprocessor 3 counts the number of black pels on a group of pel lines 4, 5, 6, 7, and 8 in rows 1-8 of the original character image with reference to histogram 26 in histogram buffer memory 4. To do. Then, the microprocessor 3 sums the numbers of black pels in each row to sample the initial position.
The total number of horizontal black pels of the pattern 21 is generated, and this total number is stored in the memory device 0 of the register 5 in the Y direction.

In the same way as above, the microprocessor 3 generates the total number of vertical black pels of the initial position sampling pattern 21. More specifically, FIG. 5A is an enlarged view of portion 28 of FIG. Pell lines 1-11 represent the pel lines of the original character image. The microprocessor 3 selects a group of pel lines 4, 5, 6, 7 and 8 for each column of the sampling pattern 21. The pel line 6 is located at the center of the width of the row, as shown in Figure 5A. The microprocessor 3 refers to the histogram 27 of the histogram buffer memory 4 to determine the number of black pels on the group of pel lines 4, 5, 6, 7, and 8 of the original character image in columns 1-8. Is counted. The microprocessor 3 then sums the number of black pels in each column to generate the total number of vertical black pels in the sampling pattern 21 at the initial position, and stores this total in the register 5 storage in the X direction. Store at 0.

Operation proceeds to block 33 of FIG. 3 where the microprocessor 3 sets the sampling pattern 21 from the initial position in the X and Y directions by ± 1 pel line, ± 2 pel line and ± 3 pel line respectively. Sequentially shift and count the total number of black pels at each position, as described for the initial position. Explaining the row or horizontal sampling operation with reference to FIG. 4B, the sampling pattern 21 is shifted upward by one pel line. First
Sampling window 25A in FIG. 4B shows a shift of sampling pattern 21 by one pel line.
The microprocessor 3 has a sampling pattern 21
Select a group of pel lines 3, 4, 5, 6 and 7 for each row of the original character image. The microprocessor 3 has the sampling pattern 21 at the +1 position.
Generate the total number of horizontal black pels in the horizontal direction, and store this total number in the Y direction memory +1 of register 5.

To shift the sampling pattern 21 to the +2, +3, -1, -2 and -3 positions, the microprocessor 3
Has pel lines 2, 3, 4, 5 and 6 for the +2 position, pel lines 1, 2, 3, 4 and 5 for the +3 position and pel line 5 for the -1 position. , 6, 7, 8
And 9 to the Pell lines 6, 7, 8, for the -2 position.
9 and 10, and the pel line 7 for the -3 position,
Select 8, 9, 10 and 11 respectively. The microprocessor 3 then selects the sampling pattern 21 at each position.
Of the horizontal black pels in the horizontal direction, and store these in each memory unit in the Y direction of register 5.

Next, as shown in FIG. 5, the microprocessor 3 sets the sampling pattern 21 from the initial position to ± 1 in the Y direction,
Shifts by ± 2 and ± 3 pel lines sequentially. In order to shift the sampling pattern 21 to the device, the microprocessor 3
Lines 5, 6, 7, 8 and 9 for the +2 position and pel lines 6, 7, 8, 9 and 10 for the +3 position and pel lines 7, 8, 9, 10 and 11 for the +3 position, Pell lines 3, 4, 5, 6, and 7 for the -1 position, Pell lines 2, 3, 4, 5, and 6 for the -2 position, and Pell lines for the -3 position. 1, 2, 3, 4 and 5 are selected respectively. The microprocessor 3 then generates the total number of vertical black pels of the sampling pattern 21 at each position and stores them in the register 5 at each memory location in the X direction.

The total number Ts of black pels at each position is expressed by the following equation.

P = S + B / t × i−B / 2t + j where P: the position of one pel line of the original character image f (P): the number of black pels on one pel line of the original character image W: of the sampling pattern Number of pel lines in a group located in the center of a row or column t: Number of dots or pels in the X or Y direction of the gray scale pattern B: One original character matrix or box X or Y Number of dots or pels in a direction S: Position of shift The range of shift positions in the positive or negative direction is represented by the following equation.

S <B / 3t In the example being described, B = 88 and t = 8, S <3.66 thus selecting shift positions of +1, +2 and +3 in the positive direction and −1 in the negative direction. -2 and -3
Shift position is selected.

Microprocessor 3 then proceeds to block 34 of FIG.
At the storage positions of the register 5 in the Y direction +3, +2,
Compare the totals stored in each of +1, 0, -1, -2 and -3 to identify the one position where the largest value is stored, and sample this identified position in the Y direction. -Select as the calibration position for pattern 21. The distance between the initial position and the calibration position of the sampling pattern 21 in the Y direction is Sy as shown in FIG.

Further, the microprocessor 3 compares the total numbers stored in the storage devices +3, +2, +1, 0, -1, -2, and -3 of the register 5 in the X direction, and the maximum value is stored. One position that is present, and selects this identified position as the calibration position for the sampling pattern 21 in the X direction. Sampling pattern in X direction
The distance between the initial position and the calibration position of 21 is Sx as shown in FIG.

FIG. 7 shows a gray scale pattern 29 generated by the prior art using the sampling pattern 21 located in the initial position of FIG. 6 without a calibration operation.

FIG. 8 shows a gray scale pattern 30 generated using the sampling pattern 21 located at the calibration positions Sx, Sy of FIG. 6 in accordance with the present invention.

Comparing the gray scale pattern 29 and the gray scale pattern 30 by observing the two portions 71 and 72 of the letter B, the portion 71 in the gray scale pattern 29 shows that the gray scale value 2 in column 2 is 2. And column 3 gray scale values 5 and 6 while portion 71 in gray scale pattern 30 is represented by column 3 gray scale value 7. And part 72 is, in the gray scale pattern 29, the gray scale values 2 and 1 in column 4 and the gray scale value 4 in column 5.
, And 2 while the portion 71 in the gray scale pattern 30 has a gray scale value of 3 in row 4
And 4 are represented. It is clear that the gray scale pattern 30 generated according to the present invention exhibits superior readability as compared to the conventional gray scale pattern 29.

The purpose of the operations performed by blocks 31, 32, 33 and 34 of FIG. 3 is to shift the sampling pattern 21 entirely on the high resolution original character image. In the overall shift of sampling pattern 21, the boundaries of the sampling windows that pass through the black lines of the characters in the initial position are such that the major part of the black lines of the characters are located between the boundaries of the sampling windows. Be shifted. Referring to FIGS. 7 and 8, the boundary 73 is the vertical line of the letter B before the overall shift of the sampling pattern 21 as shown in FIG.
It passes through 71, which makes portion 71 difficult to read, as shown by gray scale pattern 29.

After the overall shifting of the sampling pattern 21 according to the invention, the portion 71 of the letter B is positioned between the boundaries 73 and 74 of the sampling pattern 21 as shown in FIG. 8, so that the portion 71 is Gray scale pattern 30
Makes it easier to read.

In the operation of blocks 31-34 of FIG. 3, the optimum or calibrated position in the X or Y direction is detected in which the total number of black pels on a group of pel lines in the central portion of all rows or columns is maximum. Therefore, the entire sampling pattern is shifted on the original character image.

Characters are roughly classified into a first group of characters, such as alphanumeric characters, which has few horizontal and vertical lines, and a second group of characters, such as Chinese characters, which have many horizontal and vertical lines. it can.

The overall shift of the sample pattern 21 achieved by the operations of blocks 31-34 in FIG. 3 improves the readability of the first group of characters and the readability of the second group of characters, eg, Kanji. In addition to the operations of blocks 31 and 34,
Next, the operation will be further improved by the operation described with reference to FIGS. 9 to 13.

Thus, block 35 of FIG. 3 checks to see if the character being processed is a second group of characters, such as Kanji. In the case of the aforementioned alphanumeric character B, the answer to block 35 is no, and the operation proceeds to block 36, where the microprocessor 3 moves to the calibration position Sx, Sy on the original character image as shown in FIG. Positioning the sampling pattern 21 and counting the number of black pels surrounded by each sampling window of the sampling pattern 21, and varying the number of black pels in each sampling window to a different gray scale value or level 0- Assign one of the seven, so that the original character image B
The gray scale pattern 30 of FIG. The gray scale pattern 30 is then stored in the buffer memory 6 of FIG. 1 and supplied to the display device or printer.

The operation shown in FIGS. 9 to 13 is the same as the calibration position Sx of FIG.
Shift the position of the particular selected row or column of the sampling window 21 located at Sy.

Sampling pattern for Kanji as shown in Figure 10.
It is assumed that the overall shift of 21 has been completed by the operation of blocks 31-34 of FIG. 3 and that the sampling pattern 21 of FIG. 10 has been positioned at the calibration positions Sx, Sy. In this case, the answer to block 35 in FIG. 3 is yes, and operation proceeds to block 91 in FIG. 9 where the microprocessor 3 determines the calibration positions Sx, Sy of the sampling pattern 21 in FIG. select.

Operation proceeds to block 92, where microprocessor 3
Selects a group of pel lines through the central portion of each row and column of sampling pattern 21, and
Count the number of black pels on the 5 pel lines per row and column of sampling pattern 21 in Sx, Sy. The number of black pels detected in each row and column is shown in FIG.
Next, the microprocessor 3 sets the number of black pels in N rows to N
-Compare the number of black pels in row -1 and the number of black pels in row N + 1 respectively, and compare the number of black pels in row N with the number of black pels in row N-1 and the number of black pels in row N + 1 respectively Then, it detects a column or row having a number of black pels that is greater than the number of black pels of its neighbors.

The number of black pels outside the sampling pattern 21 is zero. In the example shown in FIG. 10, the microprocessor 3 is
Detect rows 1, 4 and 7 and columns 2 and 7 as indicated by the arrows in FIG. Row 1 has a value 15 greater than the value 0 of the adjacent row and the value 60 of row 2 outside the sampling pattern 21.
It has 0, ie the number of black pels. Row 4 has a value 100 which is greater than the value 60 in row 3 and the value 60 in row 5. Line 7 is line 6
Value 60 and a value 110 greater than the value 30 in row 8.
Column 2 has a value greater than the value 0 in column 1 and the value 70 in column 3 260
Have. And column 7 has a value 240 which is greater than the value 70 in column 6 and the value 0 in column 8. Therefore, microprocessor 3 selects columns 2 and 7 and rows 1, 4 and 7 as candidates to be shifted.

Operation proceeds to block 93 of FIG. 9 where microprocessor 3 shifts the positions of rows 1, 4 and 7 and columns 2 and 7 selected in block 92. This shift operation is performed by the microprocessor 3 by shifting the positions of the five pel lines from the position 0, which passes through the center of the row or column, to the positions +1, +2, -1, and -2 on the original character image. Done and 5 at each shift position
Count the number of black pels on the pel line of the book. FIG. 11 shows row 1 column 2 of the sampling pattern 21 shown in FIG.
And 3 sampling windows are shown. Referring to column 2 of this FIG. 11, a group or five pel lines are
Initially located at position 0 and then positions +1, +2,-
Shifted to 1 and -2 respectively, and position +2, +1,
The number of black pels on the 5 pel lines at each of 0, -1 and -2 is counted and stored in register 7 of FIG. It is clear from FIG. 11 that the maximum values for column 2 are obtained at shift positions +1 and +2. Of the positions +1 and +2 that produce the maximum value, the position +1 closest to the original position 0 is selected and stored in register 7. The same operation is performed for column 7, and microprocessor 3 finds that shift position-2 produces the maximum value and stores column 7 and position-2 in register 7. Row 1 will be described with reference to FIG. 11 again. In FIG. 11 it is clear that shift position -2 produces the maximum value for row 1. Then position-2 for row 1 is stored in register 7.

Similarly, microprocessor 3 finds the maximum at position 0 and -1 for row 4 and the maximum at position -1, 0 and +1 for row 7. If the original position 0 produces the maximum value, this original position 0
Is selected, so that the microprocessor 3 stores the position 0 in the shift positions of row 4 and row 7 of register 7, as shown in FIG.

In this way, the microprocessor 3 shifts the group of pel lines in the row or column selected in block 92 of the sampling pattern 21 and counts the number of black pels at each position to determine the row or column. Determines the amount of column shift.

A shift amount of 0 for rows 4 and 7 indicates that these rows are not shifted.

Operation proceeds to block 94 where microprocessor 3
Is in row 1, column 2 according to the shift value of register 7 in FIG.
And column 7 are shifted. More specifically, the microprocessor 3 shifts row 1 of the sampling pattern 21 downward by 2 pel lines, and the adjacent row 2 downward by 1 pel line, as shown in FIG. Shift to. Microprocessor 3 shifts column 2 to the right by one pel line as shown in FIG. Microprocessor 3 also shifts column 7 leftward by 2 pel lines and adjacent columns 6 and 8 leftward by 1 pel line, as shown in FIG. The purpose of shifting adjacent rows or columns in the same direction is to reduce the distortion of the character image.

Operation proceeds to block 95 in FIG. 9 where microprocessor 3 positions sampling pattern 21 on the original character image at the calibration positions Sx, Sy determined in block 34 in FIG. Shift the rows and columns as shown, count the number of black pels surrounded by each sampling window, and change the number of black pels in each sampling window to different gray scale values, levels 0-7. One of them is assigned so that the gray image representing the original Kanji image, as shown in FIG.
A scale pattern 41 is generated. The gray scale pattern 41 is stored in the buffer memory 6 shown in FIG. 1 and supplied to the display device or printer.

FIG. 13 shows the calibration position S detected in block 34 of FIG.
Gray scale pattern generated by using the sampling pattern 21 located in x, Sy, but without the specific row and column shifts shown in FIG.
42 is shown.

Comparing the gray scale pattern 41 and the gray scale pattern 42, it is clear that the readability of the top horizontal line, the left vertical line and the right vertical line of the Chinese character is significantly improved.

In the operation of FIG. 9, the position of the selected row or column of the sampling pattern in the calibration position is shifted to the position where the number of black pels in this selected row or column is maximum.

E. Effect of the Invention The present invention improves the quality and poor readability of gray scale patterns generated from high resolution original character images.

[Brief description of drawings]

FIG. 1 is a block diagram for performing an operation according to the present invention, FIG. 2 is a view showing an original character image stored in a buffer memory, and FIG. 3 is a flow chart of an operation for moving an entire sampling pattern according to the present invention, 4A. Figure, 4B
FIGS. 5A and 5B show the shift of the sampling pattern according to the invention, FIG. 6 shows the initial position of the sampling pattern and the calibration position according to the invention, and FIG. 7 shows the sampling of the prior art. Pattern position and gray scale pattern, FIG. 8 shows sampling pattern and gray scale pattern positioned in a calibration position according to the invention, FIG. 9 shows sampling pattern according to the invention 10 and 11 are flowcharts showing the operation of moving a specific row or column of the present invention, FIGS. 10 and 11 are diagrams showing the operation of selectively moving a specific row or column according to the present invention, and FIGS. 12 and 13 are samplings according to the present invention.・ Pattern and gray scale pattern are shown. Fig. 14 is a diagram showing a conventional kanji pattern and gray scale pattern. 1 ... Font memory, 2 ... Buffer memory, 3
...... Microprocessor, 4 ...... Histogram, 5 ……
Register, 6 ... Buffer memory, 7 ... Register.

Claims (9)

[Claims] 1. A method of generating a low resolution gray scale pattern representing a high resolution original character image, comprising a plurality of rows and columns arranged in a number determined by the ratio of the low resolution and the high resolution. Generating a sampling pattern having a sampling window of, and sequentially positioning the sampling pattern at a plurality of positions separated by a predetermined distance along the column direction on the original character image, and the sampling pattern at each of the positions. The total number of black pels in all the rows is counted by adding the number of black pels in a predetermined part of each row of the sampling pattern, and the total number of black pels in each of the above positions is compared to determine the position where the maximum number of black pels is detected. The sampling pattern is detected, and the sampling pattern is positioned at the detection position on the original character image. How to generate the gray scale pattern consists in counting the number of black pels in each sampling window of the ring pattern, assign one of different gray scale values to each sampling window. 2. A method according to claim 1 wherein a group of pel lines located in the central portion of said sampling window is used to count the number of black pels in said row. . 3. The sampling pattern is one pel
A method according to claim (1), wherein the method is performed by sequentially positioning at a plurality of positions separated by a line. 4. A method of generating a low resolution gray scale pattern representing a high resolution original character image, wherein a plurality of rows and columns are arranged in a number determined by the ratio of the low resolution and the high resolution. Generating a sampling pattern having a sampling window of, and sequentially positioning the sampling pattern at a plurality of positions separated by a predetermined distance along a row direction and a column direction on the original character image, Counting the total number of black pels in all rows by adding the number of black pels in each row of the sampling pattern, and the total number of black pels in all columns in each row, and the number of black pels in each row Then, compare the total number of black pels in each of the above positions,
The position in the column direction in which the total number of black pels in all the rows is the maximum and the position in the row direction in which the total number of black pels in the all columns is the maximum are detected, and the position is detected at the detection position on the original character pattern. Locating the sampling pattern, counting the number of black pels in each sampling window of the sampling pattern and assigning each of the sampling windows one of a different gray scale value How it happens. 5. A group of pel lines located in the central portion of the sampling window is used to count the number of black pels in the rows and columns. The method according to item (4). 6. The sampling pattern is one pel
A method according to claim (4), wherein the method is sequentially positioned at a plurality of positions separated by a line. 7. A method of generating a low resolution gray scale pattern representing a high resolution original character image, wherein a plurality of rows and columns are arranged in a number determined by the ratio of the low resolution and the high resolution. Generating a sampling pattern having a sampling window of, and sequentially positioning the sampling pattern at a plurality of positions separated by a predetermined distance along a row direction and a column direction on the original character image, Counting the total number of black pels in all rows by adding the number of black pels in each row of the sampling pattern, and the total number of black pels in all columns in each row, and the number of black pels in each row Then, compare the total number of black pels in each of the above positions,
The position in the column direction in which the total number of black pels in all the rows is the maximum and the position in the row direction in which the total number of black pels in the all columns is the maximum are detected, and the position is detected at the detection position on the original character pattern. Position the sampling pattern, count the number of black pels in each row and column of the sampling pattern, compare the number of black pels in each row, and select the row with more black pels than the adjacent row. Selecting columns having more black pels than adjacent columns by comparing the number of black pels in the columns, and at a plurality of positions separated by a predetermined distance along the row direction and the column direction on the original character image, Positioning the selected rows and columns sequentially, counting the number of black pels in the row at each position and the number of black pels in the column, and counting the number of black pels in the selected row at each position. Compare the black pel's There detecting the position of the column having the maximum
The number of black pels in the selected column at each position is compared to detect the position in the row direction where the number of black pels is maximum, and the position of the selected row and column is set to the detected position. Generating the gray scale pattern comprising shifting each and counting the number of black pels in each sampling window of the sampling pattern and assigning each sampling window one of a different gray scale value. Method. 8. A method according to claim 7 wherein a group of pel lines located in the central portion of the sampling window is used to count the number of black pels in the rows and columns. the method of. 9. The method of claim 7 wherein the sampling patterns are sequentially positioned at a plurality of positions separated by one pel line.